Currently traditional internal combustion automobiles and buses are gradually replaced by electric vehicles. Battery cells are the prime energy storage devices for electric vehicles. While the battery pack case as the container of battery cells is one of the key components of electric vehicles that directly affects the performance of battery cells. These key components further affect the performance of electric vehicles. Because of the excellent energy and power output and long life of lithium ion batteries, they are widely used in electric vehicles nowadays.
Battery assembly is composed of battery cells connected either in series, or in parallel. When a lithium ion battery is being charged, the aprotic solvent in the electrolyte reacts at the interface of electrode and electrolyte. The reaction forms the passivation layer covering on the electrode surface and generating hydrogen, hydrocarbons, carbon monoxide, carbon dioxide and other gases thereby increasing the internal pressure of the battery cell. This pressure severely impacts the cycle life and the safety of the battery. As the gas generation increases, the internal pressure of the battery cell increases. When it is high enough, the battery package material ruptures. Flammable gas may fill the whole battery pack. If the situation continues, the flammable gas will rupture the battery pack case. When the flammable gas meets the air, the battery pack is extremely vulnerable to explosion.
Therefore to address the above inefficiency, it is desirous to have a battery pack system, capable of detecting the leakage of batteries.